Do you understand that a security model includes allocation of finite developer resources? How much time a project's developers will spend on each class of problems?
The GrapheneOS developers have chosen a narrow set of devices that meet their hardware requirements, and that narrow list of devices allows also them to focus their resources, tightly integrate software hardening with the functioning of the hardware, and makes the project logistically manageable at all. Each clause in that sentence is part of the security model, not just the hardware requirements.
Have you ever tried to get a new build of something like LineageOS (or, once upon a time, CyanogenMod) running on a new device at all? Each ARM SoC (i.e. almost every smartphone) has numerous bespoke customizations, and its own set of largely binary-blob firmware, and often necessitates per board builds of an OS.
Adding even another half dozen devices is highly nontrivial. If you want it that badly, do the work and port GrapheneOS to those devices. Release your work downstream of the project, and benefit from its security improvements in software. It would be a good, worthy project with its own goal of bringing better security to a broader audience who are only using stock Android. That isn't the GrapheneOS project's goal.
Do you understand the purpose of the GrapheneOS project?
Its developers are in an ongoing cyber-arms-race against companies like Cellebrite and against state-level actors. The extreme hardware requirements (the primary two being Titan chips and multiyear firmware update guarantees from the vendor) are chosen with those adversaries in mind. That's their goal.
You and I are incidental users of the project. We are not its intended user: the person who needs a device that is as secure as possible against focused, well-resourced, state-level adversaries.
My stance is that I'm grateful to have access to a top-tier security tool, free and open source, way beyond my actual needs or threat model. I'm grateful it is so easy to use that the compromise (specific hardware required, 3-5% of apps I try not working) is well worth it. My stance is also that I'm against the broadening of project scope for the convenience of people who, like me, don't actually need this level of security but who, unlike me, are unwilling to make the compromise.
I'm not repeating things I've heard. I've built versions of Cyanogen and Lineage for phones I've owned over the years. I have a good idea of the work involved just getting things running at all, before even approaching the question of security. And all I'm saying is, "if you want support on devices beyond the project's scope that badly, do that work yourself and share it with the community."
You went out of your way to avoid answering the question, so it seems the answer was no.
I don't think you have a clue what you're talking about, and are indeed just repeating things you've heard. I don't see this discussion progressing further because of that, instead devolving into an is-too/is-not back and forth.
Your claim the idea that allowing Graphene on a wider array of devices would somehow weaken it's model remains nonsense, and you certainly can't support it, although if you wanted to make an effort that was more than you just asserting and repeating things, I'd be interested to consider it.
Otherwise, you have a great day.
You haven't actually made any specific arguments. Nor refuted any specific arguments I've made. You've just repeated, over and over, everything what I say is nonsense and I must be repeating things I've heard. I'd agree that sort of repetition tends to stall out discourse.
I do hope you end up with (or have already) a smartphone that is secure to your satisfaction, on the hardware that is most convenient to you, whoever ends up doing the work to make that possible. Have a good day also, and best of luck in the search for such a solution.
You're making a claim; I've asked you to support it with more than preaching, and you've been unable to do so. The lack of the discussion progressing is entirely due to that, and nothing more.